Elevator call measuring apparatus



Nov. 19, 1957 J. H. BORDEN 2,814,027

ELEVATOR CALL MEASURING APPARATUS Filed June 4. 1956 q-IB za /6 24 25 W INVENTOR.

JOS Z H BORDE/V ATmRNEYS United States Patent 2,814,027 ELEVATOR CALL MEASURING APPARATUS Joseph H. Borden, Toledo, Ohio, assignor to Haughton Elevator Company, Toledo, Ohio, a corporation of Ohio Application June 4, 1956, Serial No. 589,078

7 Claims. (Cl. 340-19) This invention relates to elevator controls and more particularly to apparatus for measuring elapsed call time in an elevator control system.

The service rendered by an elevator system is often improved by providing preferential service to one or more floors during certain portions of a day. Occasionally such service results in excessive delays in answering floor calls outside the special service region. Heretofore it has been suggested that some means should be provided to monitor the unanswered calls in the area of reduced service both as to time and number of calls. Such systerns have been quite complex including substantial numbers of both passive and active circuit elements. Thus these systems are expensive in the first instance, and in maintenance offer problems in both reliability and stability, and are of shorter life than is desirable.

In accordance with the above, the inventions principal objects are to improve elevator controls, to reduce the complexity and expense of such controls, and to increase the ruggedness and reliability of such controls. The objects of the elevator control apparatus are to improve the control of car assignments in an elevator system, to avoid excessive delays in responding to a floor call, to time the total interval one or more calls remain unanswered and to alter the dispatching program when the delay in responding to calls from a floor or group of floors exceeds a predetermined limit.

These objects are attained by means of an electrical control circuit which shifts the pattern of car travel with operational demand when that demand differs appreciably from that which is usual and for which the current operating program has been adjusted. According to one embodiment of this invention this circuit comprises a group of floor call relays each arranged to actuate an individual charging circuit which develops a charge across a condenser at a rate which can be determined by the values of the various circuit components. A group of these condensers is connected in series across the cathodegrid circuit of an electron tube so that the current flowing in the cathode-anode circuit of the tube is a function of the sum of the charge on the condensers in the group at any instant. A current sensitive relay is arranged in the cathode-anode circuit of the tube so that it controls other portions of the elevator control system, for example, to change the program employed in distributing the cars.

One feature of this invention resides in measuring the accumulated call time as the sum of the charge or voltage across a group of serially connected charge accumulators, such as condensers, wherein each condenser corresponds to a floor and the charge thereon is a function of the time which has elapsed since an unanswered call has been registered at that floor.

Another feature resides in conductively isolating the charging circuits for the individual condensers from the other charging circuits for'condensers of a group.

An additional feature involves utilizing a load circuit for an electron discharge device wherein the load is com mon to the cathode-anode and cathode-control electrode circuits. This enables the high impedance of the serially connected condensers to be effectively employed in controlling the current in a low impedance load and by virtue of the signal degeneracy introduced by the load it enlarges the range over which changes in signal level are effective in controlling load current.

A further feature consists of providing a means for rapidly discharging an individual condenser of a group when a call registered at the floor corresponding to that condenser has been answered.

The above and other objects and features of this invention will be appreciated more fully from the following detailed description when read in conjunction with the accompanying drawing wherein:

Fig. I shows one form of accumulated call time responsive circuit in accordance with this invention; and

Fig. II shows a portion of a circuit for one floor call timer of the type shown in Fig. I modified by the incorporation of a discharging means for the time accumulating condenser.

Referring now to the drawing the accumulated call time circuit of Fig. I comprises a call indicating means shown as floor call contacts 3, 4, and 5 which, for example, may be contacts on floor call relays (not shown) of the latch up type. While only three floor call circuits have been illustrated, it is to be understood that greater numbers of call circuits can be included in this control.

These contacts are normally open in the absence of an unanswered floor call. Each of these floor call contacts when closed is arranged to activate a timing apparatus which develops a quantity which is a function of the interval over which the call remains unanswered. This timing apparatus comprises a charging circuit which derives energy from the secondary winding 6 of power supply transformer 7. For convenience transformer 7 may have its primary windings 8 fed from a 117 volt, 60 cycle line and the secondary 6 may supply the conventional 6.3 volts filament voltage. Normally open contacts 3, 4, and 5 are each serially connected with primary windings 10, 11, and 12 of coupling transformers 13, 14, and 15 across secondary winding 6, whereby the closing of one or more of those contacts energizes the corresponding primary windings of transformers 13, 14, and 15.

The secondary windings 16, 17, and 18 of transformers 13, 14, and 15 are each connected across a first condenser 20, 21 or 22 respectively, through a polarizing rectifier 23, 24 or 25 so that the voltage across the first condenser is of a desired polarity and rises almost to the peak voltage developed across the secondary very rapidly. In a typical circuit the coupling transformers can have a 1:1 ratio of turns, a semiconductive rectifier element such as a silicon diode can be employed to establish the desired polarity and the first condenser can be of about 0.5 microfarad whereby a potential of about 8.9 volts is developed across that condenser 20, 21 or 22 with its left-hand terminal positive with respect to its right-hand terminal.

This polarized voltage maintained by first condenser 20, 21 or 22 gradually charges a second or timing condenser 26, 27 or 28 connected across the corresponding first condenser through a resistor 30, 31 or 32 which aids in determining its charging and discharging rate. In a circuit having the above illustrative values, a resistor 30 of 22 megohms and a timing condenser 26 of 2 microfarads, the time constant of the circuit is about 44 seconds. These second or timing condensers 26, 27, and 28 thus provide charge accumulating means which exhibit a charge which is a function of the interval over which an unanswered call has been registered.

In an elevator control system this information provided by the charge on the timing condensers is particularly useful 'in avoiding untimely delays in service. In particular, if. a system operated to offer only limited service to the second, third and fourth floors were subjected to an unusual demand resulting in excessive delays in responding to calls on these floors, the service ofiered can be improved by employing this information to indicate the desirability of shifting or to shift automatically to another program which better satisfies this demand. This is accomplished by monitoring the charge and actuating the indicator or control when the signal level representing the sum of the unanswered call intervals for those floors reaches a predetermined limit. Means for effectively summing those intervals comprising means for summing the accumulated charge on the respective timing condensers for said fioors is aiforded by serially connecting these condensers to an electroresponsive device which in turn controls an indicator or program controller. One such electroresponsive device is an electron discharge device 33 having an anode 34, a cathode 35, and a control electrode 36 and having a resistor 37 and a relay 38 connected as its load in the common portion of its cathode-anode and cathode-control electrode circuit. This configuration is particularly advantageous in combination with a signal source comprising charged condensers since it provides an electrostatic responsive means having a high input impedance which effectively couples the high impedance signal source and a low impedance load.

The plate supply for electron tube 33 is a secondary winding 40 of power transformer 7 connected to the anode and cathode through a rectifier 41 poled to apply a positive potential to the plate. Filtering of the plate voltage is afforded by condenser 42 connected across secondary 40.

This circuit has been operated with an eight floor call time summing arrangement having the above set forth parameters when fed to a 6817 type tube connected for triode operation with the screen and suppressor tied to the anode, a 150 volt plate voltage, a 2 microfarad condenser 42, and a 23,000 ohm load 37 and 38, to pick up the armature of relay 38 when 4.9 volts is applied across its coil. Relay operation occurs when the total accumulated unanswered time for calls registered simultaneously at three floors is 28.5 seconds, at four floors having simultaneously registered calls is 19.5 seconds or on six floors having simultaneously registered calls is 11.4 seconds. One circuit which is well adapted for elevator control systems has employed a load comprising a relay coil 38 offering 5,000 ohms resistance which picks up at 4.9 volts and drops out at 3.8 volts and a loading resistor 37 of 18,000 ohms. It is to be understood that the accumulated charge on the timing condensers required to operate the relay can be reduced by reducing load resistor 37 and increased by increasing that resistor.

In some instances it may be desirable to eliminate the residual charge in a timing condenser associated with a floor call which has been answered from the sum of the charges influencing the control elements. This can be accomplished in the manner shown in Fig. II by providing in each floor call timing circuit a discharge path for the timing condenser which is closed when a floor call is answered. The resistor 43 offers such a path when contacts 44 are closed. The contacts 44 may conveniently be normally closed contacts of the floor call relay also controlling normally open contacts 3. Thus the discharge can be effected by the latching up of the floor call relay as a result of a car answering the call, when they are contacts of that relay, in response to the operation of a circuit controlled by that relay, or by any other convenient means of recognizing that the call at that floor has been answered. In the absence of this feature the disclosed system operates in response to a predetermined average level of activity. The incorporation of this feature affords a means of avoiding unwarranted shifts in the car program when one call which had remained unanswered for a sufficient interval to develop a substantial charge in its timing condenser is answered, since the normally slow decay of that charge will be accelerated removing it from the of the other accumulated charges.

It is to be understood that the above disclosed embodi ments of this invention are presented for purposes of illustration and that those skilled in the art will be able to modify those embodiments without departing from the spirit or scope of this invention. In particular, other forms of charging circuits might be employed with the timing condensers, other forms of high input impedance signal translators might be substituted for the electron tube shown including semi-conductive devices and other forms of discharge devices, and other load actuating schemes might be incorporated including those responding to a drop in current in the translator. In the embodiment shown a load responsive to the fall in current below a predetermined level can be actuated by reversing the polarity of the rectifiers 23, 24, and 25 so that the cathodecontrol electrode signal becomes more negative as the sum of unanswered call intervals increases thereby reducing the cathode-anode current.

Having described the invention, I claim:

1. In an elevator system in which a call registering control is provided for each of a plurality of fioors, apparatus for measuring the total time that the calls at said plurality of floors remain unanswered comprising, a condenser for each of said controls, a charging circuit for each of said condensers responsive to the actuation of said corresponding floor controls, a plurality of said condensers being arranged in series, and an electroresponsive device connected to the serially arranged condensers and responsive to a predetermined sum of the charge on said condensers.

2. In an elevator system in which a call registering control is provided for each of a plurality of floors, apparatus for measuring the total time that the calls at said plurality of floors remain unanswered comprising, a condenser corresponding to each of said controls, a charging circuit for each of said condensers responsive to the actuation of said corresponding floor controls, a plurality of said condensers being arranged in series, a pair of terminals for each condenser conductively isolated from every other pair of condenser terminals, and an electrostatic responsive device connected to the serially arranged condensers and responsive to a predetermined sum of the charge on said condensers.

3. An apparatus in accordance with claim 1 including a discharge path for each of said condensers, and means to open said discharge path upon the actuation of said call registering control, to maintain said path open until the call which actuated said call registering control has been answered and to close said path when said call is answered.

4. In an elevator system in which a call registering control is provided for each of a plurality of floors, apparatus for measuring the total time that the calls at said plurality of floors remain unanswered comprising, a plurality of first condensers, a plurality of first circuit portions individually connected to said controls each including one of said first condensers, said first circuit portions having a short charging time constant, a plurality of second condensers, a plurality of second circuit portions each including one of said second condensers and each connected across one of said first condensers, said second circuit portions having a charging time constant exceeding several seconds, means responsive to the actuation of individual of said control circuits for applying a potential across said first and second condensers corresponding thereto, a plurality of said second condensers being arranged in series, and an electroresponsive device connected to the serially arranged condensers and responsive to a predetermined sum of potentials developed across said condensers.

5. In an elevator system in which a call registering control is provided for each of a plurality of floors, apparatus for measuring the total time that the calls at said plurality of floors remain unanswered comprising, individual charging circuits for each floor each actuated by said call registering control for that floor, first means connected to each charging circuit for accumulating a charge in an amount which is a function of the interval over which said circuit is actuated, means for summing the accumulated charge developed in said first means by said charging circuits, an electroresponsive device, and means applying a signal corresponding to the sum of accumulated charge to said electroresponsive device.

6. In an elevator system in which a call registering control is provided for each of a plurality of floors, apparatus for measuring the total time that the calls at said plurality of floors remain unanswered comprising, individual charging circuits for each floor each actuated by said call registering control for that floor, first means connected to each charging circuit for accumulating a charge in an amount which is a function of the interval over which said circuit is actuated, means for summing the accumulated charge developed in said first means by said charging circuits, an electron discharge device having cathode, anode and control electrodes, said summing means being connected across said discharge device cathode and control electrodes, and an electroresponsive means in the anode to cathode circuit of said electron discharge device.

7. In an elevator system in which a call registering control is provided for each of a plurality of floors, apparatus for measuring the total time that the calls at said plurality of floors remain unanswered comprising, indi vidual charging circuits for each floor each actuated by said call registering control for that floor, first means connected to each circuit for accumulating a charge in an amount which is a function of the interval over which said circuit is actuated, means for summing the accumulated charge developed in said first means by said charging circuits, an electron discharge device having cathode, anode and control electrodes, said summing means being connected across said discharge device cathode and control electrodes, and an electroresponsive means in a common portion of the anode-cathode and cathode-control electrode circuits of said electron discharge device operable when the sum of the accumulated charge attains a predetermined value.

References Cited in the file of this patent UNITED STATES PATENTS 1,942,415 Federici June 9, 1934 2,329,048 Hullegard Sept. 7, 1943 2,374,248 Tuttle Apr. 24, 1945 2,501,320 Eames Mar. 21, 1950 

